1. Field of the Invention
This invention relates generally to audio systems, and more particularly to portable audio speakers.
2. Related Art
The continuing miniaturization of electronic devices has led to a variety of portable audio devices that deliver audio to a listener via headphones. Portable radios have evolved from AM and/or FM radios to more recently available portable satellite radios. Portable audio devices are also available for playing audio tapes, compact discs (CDs), mini-audio discs, and more recently, audio recorded on solid state or magnetic storage devices. Examples of solid state and magnetic storage devices include the iPod™ from Apple.
The miniaturization of electronics has also led to smaller and smaller headphones that produce high quality sound. Even earphones, or headphones that plug directly into the user's ears, are now capable of delivering rich, high quality sound that silences external sounds generated in the user's environment.
Portable audio devices now offer users a virtually unlimited selection of audio sound and music as well as the ability to listen to such audio and music through high quality sound sources. Portable audio devices have become so advanced and so small that users “wear” their portable audio devices while engaged in a wide variety of activities such as exercising, commuting, working, etc.
Users often use their portable audio devices in situations in which the advantages of rich sound that silences external sound from the user may actually be a shortcoming. For example, there may be safety reasons for why a user should be able to hear noise generated in his environment. Such situations may include for example, if a user is running for exercise outdoors, and there may be areas of traffic in which the user may need to hear the sounds generated in the environment to avoid being involved in an accident. It may also be desirable in situations for a user to be able to hear the sounds from the surrounding environment. Such situations may include social situations in which it may appear impolite to have headphones on so that the user can't hear what others are saying. In other situations, it may simply be inconvenient to be completely isolated from external sound. For example, the user may be waiting to hear an announcement from a public address system.
It would be desirable to allow a user to adjust the extent to which the user may hear external sounds while wearing a portable audio device.